1. Field of the Invention
The present invention relates to an optical information recording and reproducing apparatus, and more particularly to an optical information recording and reproducing apparatus capable of checking a loading state of an optical information recording medium. The present invention may be preferably applied to an optical information recording/reproducing apparatus which uses a card-like optical information recording medium.
Media for recording information for and reproducing such recorded information by light beams include disks, cards and tapes. Such media include ones which permit recording and reproducing of information and ones which permit only reproducing of information.
Information is recorded on such a recording medium by scanning information tracks with a light beam modulated in accordance with record information and focused to a fine spot so that the information is recorded as an optically detectable information bit train.
Information is reproduced from the recording medium by scanning the information bit train on the information tracks with a light beam spot of a predetermined power which is small enough to inhibit recording on the recording medium, and by detecting reflected light or transmitted light from the medium.
An optical head is used to irradiate a light beam spot to the recording medium and to detect the reflected light or transmitted light from the medium. The optical head is movable relative to the recording medium along and across the information tracks so that the information tracks are scanned by the light beam.
Of the optical information recording media, the card-like optical information recording medium (hereinafter referred to as an optical card) is compact, light in weight, easy to carry, and of large capacity. Thus, a large demand is expected for such a medium.
FIG. 1(a) shows a schematic plan view of an optical card and FIG. 1(b) shows a sectional view taken along line B--B thereof.
A format of an optical card is disclosed in detail in U.S. patent application Ser. No. 07/033,189, filed Apr. 3, 1987, now abandoned in favor of copending application Ser. No. 07/479,205 and assigned to the assignee of the present invention.
In FIGS. 1(a) and 1(b), numeral 1 denotes an optical card. A surface of the optical card 1 includes an information record area 31 and a blank area 32, other than the record area. The blank area 32 may include an appropriate logo 33 so that a user can visually identify the type or application of the optical card. In the information record area 31, a plurality of tracking tracks 34, preformatted for auto-tracking are arranged in parallel. Areas between adjacent tracking tracks are information tracks 35 on which information is recorded.
As seen from FIG. 1(b), the optical card 1 includes a plurality of layers. Numeral 36 denotes a transparent protective layer, and numeral 37 denotes a record layer. The record layer may be made of silver halide, dye or calcogen. A boundary between the transparent protective layer 36 and the record layer 37 has steps by which the tracking tracks 34 and the information tracks 35 are formed. Numeral 39 denotes a substrate which is bonded to the record layer 3 by a bonding layer 38.
FIG. 2 shows a block diagram of an apparatus for recording information on the optical card and/or for reproducing the information recorded on the optical card. Such a block diagram is disclosed in U.S. Pat. No. 4,751,394.
In FIG. 2, numeral 1 denotes an optical card which is securely mounted on a shuttle 5 in a position perpendicular to a direction indicated by double-head arrow B. The optical card 1 is loaded such that the tracking tracks and the information tracks are oriented in a direction indicated by double-head arrow A.
Numerals 22 and 23 denote pulleys. A belt 24 spans between those pulleys, and the shuttle 5 is fixed to the belt. The pulley 22 is mounted on a shaft of a drive motor 26. The belt 24 is driven by forward or backward rotation of the motor so that the shuttle 5 is reciprocally moved in the direction A.
Numeral 3 denotes an optical head which contains a semiconductor laser 8 as a light source, a collimater lens 9, a polarization beam splitter 10, a quarter wavelength plate 30, an objective lens 11 and a photo-sensor 12. The optical head 3 is intermittently driven by a stepping motor 21 in a direction C (normal to the plane of the drawing).
A light beam from the laser 8 passes through the collimater lens 9, the polarization beam splitter 10 and the quarter wavelength plate 30, and is focused by the objective lens 11 into a light beam 4, which forms a fine spot on the optical card 1. Light of the light beam reflected by the optical card 1 passes through the objective lens 11 and the quarter wavelength plate 30, and is reflected by the polarization beam splitter 10 to the photo-sensor 12.
An output of the photo-sensor 12 is applied to a preamplifier 13 which produces a focusing error signal and a tracking error signal, which are supplied to auto-focusing servo means 14 and auto-tracking servo means 15, respectively, which in turn issue commands for auto-focusing and auto-tracking to drive mechanisms (not shown) to move the objective lens 11 in the directions of B and C, respectively.
On the other hand, the reproduced information signal from the preamplifier 13 is applied to a decoder 16, an output of which is supplied to a computer 18 through an interface 17.
The computer 18 issues a command signal to the laser 8. The command signal reaches the laser 8 through the interface 17, an encoder 19 and a laser driver 20. The computer 18 also issues a command signal for the stepping motor 21. The command signal reaches the stepping motor 21 through the interface 17. The computer 18 further issues a command signal for the drive motor 26. The command signal reaches the motor 26 through the motor servo means 27.
In the above recording/reproducing apparatus, information is recorded on the optical card 1 and/or reproduced from the optical card 1 by intermittently moving the optical head 3 in the direction C while the optical card 1 is reciprocally moved in the direction A at a predetermined stroke while being irradiated by the semiconductor laser 8.
For recording and/or reproducing information, the optical card 1 is manually inserted in the direction A from a card insert port and mounted on the shuttle 5 which conveys the optical card to the recording or reproducing position.
There are several orientations for the optical cards when inserted from the card insert port. Namely, the cards may be inserted in a normal orientation, in an inverted orientation or in a reverse (up-side down) orientation.
When the optical card is inserted in the inverted or reverse orientation, the surface of the transparent protective layer 36 of the optical card may be damaged. If the transparent protective layer is damaged in the information record area 31, the focusing state of the light beam 4 is disturbed and normal recording/reproducing of information may not be attained.
Accordingly, it is necessary to determine whether the optical card has been inserted in the normal orientation.
In the prior art information recording/reproducing apparatus, in order to determine whether the optical card has been loaded at the predetermined position on the shuttle in the normal orientation, an optical card having a small hole at one corner thereof is used. The optical card is illuminated from one side of the optical card and a photo-detector arranged on the other side of the optical card detects a light input. In this method, however, the optical card must be a special one having the small hole formed therein.
U.S. Pat. No. 4,751,394 discloses an optical information recording/reproducing apparatus which permits determination of a loading status of an optical card without using a special form of optical card. In the disclosed apparatus, an illumination light is irradiated from the optical head to the optical card, light reflected from the optical card is detected by a photo-detector, and the load status of the optical card is determined in accordance with the detected light intensity by utilizing a difference between reflection factors at different areas on the optical card. In the disclosed apparatus, however, the reliability of such a determination is low when an optical card having a small difference in reflection factors of the information record area 31 and the blank area 32 of FIG. 1(a) is used, or when an optical card having a small difference in reflection factors between the front side and the back side is used. In the disclosed apparatus, the optical card must be manufactured by using different materials for the front side and back side.
However, optical card of a type which is not anticipated to be used may be loaded into the recording/reproducing apparatus. Accordingly, it is desirable to determine the orientation of loading as well as whether the loaded optical card is a predicted one or not.
U.S. patent application Ser. No. 06/838,443, now abandoned in favor of copending application Ser. No. 07/374,626 and assigned to the assignee of the present invention discloses a method for detecting an information recording medium having a different characteristic by detecting a level of a reflected or transmitted light of an information detecting light beam from an information recording medium. In this method, however, each of the information recording media used must have a different reflection factor or different transmission characteristic.